The production of sweeteners from starch has been largely improved by application of different microbial enzymes to obtain better quality and yields, but the necessity of performing several steps of the starch-hydrolysing process at elevated temperatures means that there is still a need for new starch-hydrolysing enzymes with increased thermal stability.
It is known that Pyrococcus, e.g. Pyrococcus woesei and Pyrococcus furiosus, for reference see Arch. Microbiol. 155, 1991, pp. 572-578, and Appl. Env. Microbiol. 56, 1990, pp.1985-1991, can produce highly thermostable amylases.
The paper and pulp industry is using xylanase compositions in the bleaching process to enhance the brightness of bleached pulps, to decrease the amount of bleaching chemicals, e.g. chlorine, used in the bleaching stages, and to increase the freeness of pulps in the recycled paper process.
Thermostable xylanases from Thermotoga have been described, for reference see Biochem. J. 277(2), 1991, pp. 413-418.
It is the object of this invention to provide a xylanase, an amylase and a pullulanase with temperature optimum at 100.degree. C. or above 100.degree. C.